Timbuktu, the fabled desert city where retreating Muslim extremists destroyed ancient manuscripts, was a center of Islamic learning hundreds of years before Columbus landed in the Americas.

It is not known how many of the priceless documents were destroyed by al Qaida-linked fighters who set ablaze a state-of-the-art library built with South African funding to conserve the brittle, camel-hide bound manuscripts from the harshness of the Sahara Desert climate and preserve them so researchers can study them.

News of the destruction came Monday from the mayor of Timbuktu. With its Islamic treasures and centuries-old mud-walled buildings including an iconic mosque, Timbuktu is a U.N.-designated World Heritage Site.

The damage caused by the fleeing Islamists was limited, but irreplaceable treasures were lost.

Most of the manuscripts, which are as many as 900 years old, were gathered between the 1980s and 2000 from all over Mali for the Ahmed Baba Institute for Higher Learning and Islamic Research, which moved into its new home in 2009.

The library held about 30,000 manuscripts of which only about one third had been catalogued, according to its Web site. The world may never know what it has lost.

The manuscripts cover subjects ranging from science, astrology and medicine to history, theology, grammar and geography. All are in Arabic script, in the Arabic language and African languages.

They date back to the late 12th century, the start of a 300-year golden age for Timbuktu as a spiritual and intellectual capital for the propagation of Islam on the continent.

Michael Covitt, chairman of the Malian Manuscript Foundation, called them “the most important find since the Dead Sea Scrolls.”

Tens of thousands more manuscripts – no one knows how many – were kept at other libraries and private homes in Timbuktu. Some are believed to have been secreted against the Islamist fighters, who began their desecration of the city by systematically razing the 15th-century mausoleums of several Sufi saints in July. Among the tombs they destroyed is that of Sidi Mahmoudou, a saint who died in 955, according to a UNESCO website.

The International Criminal Court at The Hague has described the destruction of Timbuktu’s heritage as a possible war crime. Timbuktu has been attacked and conquered in the past, most recently in 1591 by Moroccan troops who sacked the city and burned libraries. But the city recovered and gained fame as a place where people from different races and creeds could live together harmoniously.

Even before Europeans landed in the Americas, Timbuktu had a population of 30,000.

The nomadic Tuareg tribe first set up their camel-skin and palm-mat tents there in the dry season, attracted by its location where the Niger River flows toward the southern brink of the Sahara Desert, prompting some to call it the point where “the camel meets the canoe.” The tents gave way to sun-dried terracotta-colored mud brick buildings built in the Moorish style as traders, medical doctors, clerics, artists, poets and others settled there.

The city is on an old caravan route where Arab traders brought salt and other goods that reached North Africa’s Mediterranean shores and traded it in Timbuktu for gold and Islamic books. It served as a major crossroads between Africa’s Arab north and black West Africa, bringing together black Africans, Berbers, Arabs and the Tuareg people that consider Timbuktu their town. Its dynamism has been overlooked by the English expression “from here to Timbuktu” – conjuring up an end-of-the-earth remoteness.

Islamist extremists decimated tourism in 2011 when three Europeans were taken hostage from a Timbuktu restaurant in November that year, frightening away visitors. In April 2012, Tuareg nationalist rebels seized control of Timbuktu from government troops. A day later Islamist insurgents elbowed their way into the city. They banned music, insisted women cover themselves and began carrying out public executions and amputations.

On Tuesday, Timbuktu was in control of French and Malian troops, including some 250 French paratroopers dropped from the sky. The extremists melted into the desert without firing a shot. Townspeople were jubilant at the city’s liberation from intolerant Islamist extremists.